Abstract: Procedure for draining of sludge, especially flocculent flotation sludge, including introducing water-sludge mixture into a settling tank with an overflow and removing the settled sludge layer from the settling tank with a slanted conveyor. Horizontal grooves are then pressed in the sludge layer by section roller rows arranged over the slanted conveyor belt. The water extracted from the sludge layer is collected and canalized in these horizontal grooves. The back-flowing water is then collected and guided off in water drainage systems arranged over the slanted conveyor. These water drainage systems are tilted toward and enter a front side of the horizontal grooves. This collected water may either be eliminated directly or returned to the settling tank.

Abstract: The invention relates to a process for separating mineral finest grain from coal slurries or washings obtained in coal processing, by treating the washing with a selective anionic dispersing agent for the finest grain, having a molecular weight of .ltoreq.10000 g/mol, and subsequent selective flocculation of the coal by means of a flocculating agent known per se.